Superfoods Research & Evidence-Based Practice 2 — Questions and Answers
Question 1: What does a 'randomized controlled trial' (RCT) on superfoods provide that an observational study cannot?
- Direct evidence of cause and effect (Correct answer)
- Larger sample sizes
- Longer follow-up periods
- More diverse food exposures
Correct answer: Direct evidence of cause and effect
RCTs randomly assign participants to treatment or control groups, allowing researchers to isolate the effect of a specific superfood and establish causation rather than mere correlation.
Question 2: A study finds that blueberry consumption is associated with lower blood pressure in people who also exercise regularly. This is best described as an example of:
- Effect modification (interaction) (Correct answer)
- Confounding
- Selection bias
- Publication bias
Correct answer: Effect modification (interaction)
Effect modification occurs when the relationship between two variables (blueberries and blood pressure) changes depending on a third variable (exercise level).
Question 3: Which biomarker is most commonly used in studies to assess the antioxidant effects of superfoods in vivo?
- Plasma F2-isoprostanes (Correct answer)
- Serum albumin
- Fasting glucose
- C-reactive protein alone
Correct answer: Plasma F2-isoprostanes
F2-isoprostanes are stable oxidative stress markers formed from lipid peroxidation and are considered a reliable biomarker of oxidative damage in human studies.
Question 4: The PREDIMED trial is frequently cited in superfood research. What dietary pattern did it primarily investigate?
- Mediterranean diet supplemented with olive oil or nuts (Correct answer)
- Paleo diet with superfood supplements
- DASH diet with added superfoods
- Vegan diet with omega-3 fortification
Correct answer: Mediterranean diet supplemented with olive oil or nuts
PREDIMED (Prevención con Dieta Mediterránea) studied the Mediterranean diet supplemented with extra-virgin olive oil or mixed nuts versus a low-fat control diet for cardiovascular outcomes.
Question 5: When a superfood study reports a relative risk reduction of 30% but the absolute risk reduction is only 0.3%, which interpretation is more clinically meaningful?
- The absolute risk reduction, because it reflects real-world impact (Correct answer)
- The relative risk reduction, because it shows biological potency
- Both are equally meaningful for clinical decisions
- Neither; only NNT matters
Correct answer: The absolute risk reduction, because it reflects real-world impact
Absolute risk reduction tells practitioners how many fewer events occur per 100 people treated, making it more actionable than relative figures that can seem large even with tiny baseline risks.
Question 6: A meta-analysis on omega-3 fatty acids and cognitive decline shows high heterogeneity (I² = 85%). What does this mean for interpreting the pooled result?
- The studies varied greatly, so the pooled estimate should be interpreted cautiously (Correct answer)
- The pooled estimate is highly reliable
- The meta-analysis should be discarded entirely
- More studies are needed before any analysis is valid
Correct answer: The studies varied greatly, so the pooled estimate should be interpreted cautiously
An I² of 85% indicates substantial between-study variability, suggesting differences in populations, dosing, or methods that limit confidence in the overall pooled effect size.
Question 7: In superfood research, the 'food matrix' refers to:
- The physical and chemical structure of food that affects nutrient absorption (Correct answer)
- The list of nutrients on a food label
- A database of superfood clinical trials
- The network of agricultural supply chains
Correct answer: The physical and chemical structure of food that affects nutrient absorption
The food matrix encompasses how nutrients are physically embedded in food structures (cell walls, fat globules, fiber networks), which profoundly influences bioavailability and health effects.
Superfoods Research & Evidence-Based Practice 2
What does a 'randomized controlled trial' (RCT) on superfoods provide that an observational study cannot?